From: Florian Fainelli <florian.fainelli@broadcom.com>
Date: Mon, 18 Aug 2025 15:50:48 +0000 (-0700)
Subject: cpufreq: scmi: Account for malformed DT in scmi_dev_used_by_cpus()
X-Git-Tag: v6.18-rc1~49^2^2~2^2~19
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cd5d4621ba846dad9b2e6b0c2d1518d083fcfa13;p=thirdparty%2Fkernel%2Flinux.git

cpufreq: scmi: Account for malformed DT in scmi_dev_used_by_cpus()

Broadcom STB platforms were early adopters (2017) of the SCMI framework and as
a result, not all deployed systems have a Device Tree entry where SCMI
protocol 0x13 (PERFORMANCE) is declared as a clock provider, nor are the
CPU Device Tree node(s) referencing protocol 0x13 as their clock
provider. This was clarified in commit e11c480b6df1 ("dt-bindings:
firmware: arm,scmi: Extend bindings for protocol@13") in 2023.

For those platforms, we allow the checks done by scmi_dev_used_by_cpus()
to continue, and in the event of not having done an early return, we key
off the documented compatible string and give them a pass to continue to
use scmi-cpufreq.

Fixes: 6c9bb8692272 ("cpufreq: scmi: Skip SCMI devices that aren't used by the CPUs")
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index ef078426bfd51..38c165d526d14 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -15,6 +15,7 @@
 #include <linux/energy_model.h>
 #include <linux/export.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/pm_opp.h>
 #include <linux/pm_qos.h>
 #include <linux/slab.h>
@@ -424,6 +425,15 @@ static bool scmi_dev_used_by_cpus(struct device *scmi_dev)
 			return true;
 	}
 
+	/*
+	 * Older Broadcom STB chips had a "clocks" property for CPU node(s)
+	 * that did not match the SCMI performance protocol node, if we got
+	 * there, it means we had such an older Device Tree, therefore return
+	 * true to preserve backwards compatibility.
+	 */
+	if (of_machine_is_compatible("brcm,brcmstb"))
+		return true;
+
 	return false;
 }